21333781221 has 16 divisors (see below), whose sum is σ = 30045480960. Its totient is φ = 13443640560.

The previous prime is 21333781213. The next prime is 21333781243. The reversal of 21333781221 is 12218733312.

It is not a de Polignac number, because 21333781221 - 2³ = 21333781213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21333781201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2663391 + ... + 2671388.

It is an arithmetic number, because the mean of its divisors is an integer number (1877842560).

Almost surely, 2^21333781221 is an apocalyptic number.

It is an amenable number.

21333781221 is a deficient number, since it is larger than the sum of its proper divisors (8711699739).

21333781221 is a wasteful number, since it uses less digits than its factorization.

21333781221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5334856.

The product of its digits is 12096, while the sum is 33.

The spelling of 21333781221 in words is "twenty-one billion, three hundred thirty-three million, seven hundred eighty-one thousand, two hundred twenty-one".